1. Field of the Invention
This invention relates to a liner assembly for rock crushers; particularly, the invention relates to the multi-sectional mantle liner in a gyratory type crusher; more particularly, this invention relates to gyratory crusher which has sections of liner of different performance characteristics making the liner especially wear resistent, easily replaceable and of outstanding overall performance.
2. Description of the Prior Art
Gyratory type crushers are used in the mining industry for reducing ore to a predetermined size for further processing. The development of improved supports and drive mechanisms has allowed gyratory crushers to take over most large hard-ore and mineral-crushing applications and has made these an integral part of the mining industry. Typically, a gyratory crusher comprises a stationary conical bowl or mortar which opens upwardly and has an annular opening in its top to receive feed material. A conical mantle or pestle opening downwardly is disposed within the center of the larger bowl which is eccentrically oscillated for gyratory crushing movement with respect to the bowl. The conical angles of the mantle and bowl are such that the width of the passage decreases toward the bottom of the working faces and may be adjusted to define the smallest diameter of product ore. The oscillatory motion causes impact with some attrition as a piece of ore is caught between the working faces of the bowl and mantle. Furthermore, each bowl and mantle includes a liner assembly replaceably mounted on the working faces, and these liners define the actual crushing surface.
A substantial amount of prior art exists relating to gyratory mantle lining assemblies, however, none of it discloses the present invention or its advantages.
For example, U.S. Pat. No. 3,850,376 relates to a mantle for a gyratory crusher whereby the mantle lining has a concentric groove which supposedly permits the mantle lining to flow into this groove when crushing ore thereby reducing the bulging of the liner.
U.S. Pat. No. 3,834,633 relates to a mantle lining assembly for a gyratory crusher having a plurality of arcuate segments, arranged in a ring fashion on the backing plate, and secured thereto with a resilient adhesive such as polyurethane.
U.S. Pat. No. 3,406,917 and U.S. Reissue No. 26,923 relates to a lining ring assembly for gyratory type crushers having a plurality of segmented members which fit together with one another on the mounting ring to provide the desired grinding surface.
U.S. Pat. No. 3,064,909 relates to a protective ring for the locking nut which retains the mantle element on the central shaft assembly of the gyratory type crusher.
U.S. Pat. No. 2,913,189 relates to a mantle design for a gyratory crusher whereby the process of zincing is simplified. This zincing process, in conjunction with a liner backing design, supposedly keeps the mantle and liner tightly mounted as a single unit.
U.S. Pat. No. 1,423,792 relates to a mantle lining assembly for a gyratory crusher whereby the upper and lower mantle sections are held together by locking keys.
U.S. Pat. No. 1,154,100 relates to a mantle lining assembly for a gyratory crusher whereby the upper and lower mantle sections are locked together by an interlock design of the same.
U.S. Pat. No. 1,151,199 relates to a mantle assembly for a gyratory type crusher whereby the upper and lower mantle sections are locked together by a helical end surface design of the same.
U.S. Pat. No. 1,066,277 relates to a mantle assembly for a gyratory type crusher whereby the upper and lower mantle sections are locked together by an S-shaped end surface design of the same.
By far, the largest operating expense for a gyratory crusher unit is associated with relining. It is standard practice for the liner of a gyratory crusher mantle to be of one basic shape and of one type of material, as shown in FIG. 2 herein, illustrating the prior art. The crusher mantle assembly is a conical-shaped main shaft with upper and lower bearing surfaces, and a mantle liner piece secured by a retaining nut. The liner of the mantle is a metal sleeve or outer-skin which is replaceable. Typically, the liner has a fundamental shape of a hollow frusto-conical section opening downwardly which fits over the conical shaped main shaft. In order to secure the liner to the mantle, a retaining nut forces the liner downward onto the mantle thereby preventing axial movement of the liner relative to the mantle. The preferred lining material which is generally used is manganese steel which is soft until it becomes work-hardened. The work-hardening process occurs during the act of rock crushing which may develop a surface hardness up to approximately 600 Brinell Hardness Number.
However, single liners have several disadvantages, principally, their large size makes them extremely costly per ton of ore crushed. A further component of the cost is in the changing of the conical liner. It is labor-wise costly to change a single mantle liner because the main shaft must be completely removed from the gyratory crusher before a worn liner can be changed. As a consequence, in continuous ore crushing operations where machine down-time is critical, it is costly to have an inoperative, idle ore crusher.
Another disadvantage of the single liner is the problem of improper wear-in or work-hardening. This problem exists because different ore types do not properly work-harden a manganese steel liner to high surface hardness thereby resulting in less than optimum wear life, and increased crushing cost.
In an attempt to overcome the problems of these increased production costs and the problems of rapid liner wear associated with single mantle liners of the prior art, multi-sectional liners have been proposed. The prior art principally sought to overcome the manufacturing costs of construction by reducing the size of each liner section. Typically, the area of greatest stress in a gyratory crusher or the area where the greater part of mantle liner wear occurs is on the bottom or lower half of the liner. It is here that the mantle is subjected to the hardest crushing work and, thus, the greatest wear. Accordingly, as shown in FIG. 3 herein, illustrating another approach by the prior art, multi-sectional liners were developed so that only the worn lower half would need replacement, thereby reducing costs.
In the prior art, different materials have been proposed to solve the problem of this inadequate work-hardening of a liner by using hard metal alloys such as either martensitic white iron or martensitic steel. Metal alloy materials which are ideal from the standpoint of abrasion resistance, however, are difficult to use and manufacture. These alloys are more brittle and undergo significant dimensional change as these are heat treated during manufacture. Furthermore, an inherent risk in using large conical heat-treated alloy liners in ore crushing operations is the possibility of catastrophic failure which is caused by the brittle and crack-sensitive nature of these alloys. Unlike the concave liners of the bowl which are held in place by the geometry of their arched structure, the mantle liners are free to fall off once cracking is initiated thereby jamming the gyratory crusher.
The need to secure each liner to the mantle core in order to prevent the movement of the liner is a disadvantage of historically known multi-sectional mantle liner assemblies. The prior art principally sought to overcome these problems through the process of zincing, which involves pouring molten zinc into channels or grooves on the posterior surface of the mantle liner, thereby securing the liner to the main shaft. Although zinc has historically been used as a liner locking device that often is no longer the case. More recently NORDBACK.TM. type plastic compounds have been used as backing material. Once a liner is in place, as described for the zinc, the poured NORDBACK.TM. fills in all voids and provides a close form fitting backing. These materials serve two purposes: a) providing a close tolerance backing to prevent a liner from "rattling" and experiencing deformations; and b) serving as a barrier between the liner(s) and mainshaft which protects the expensive mainshaft dimensions from being eroded due to many minute liner movements during its useful life.
Another method for securing the liner sections, which interlocks the liner and mantle core, provides slots for insertion of a steel bar. This bar joins and locks both sections and, further, prevents axial movement of the mantle liner relative to the mantle core. Still another proposed method to interlock the liner sections is to have an interlocking posterior surface design and to use zincing to secure the same to the mantle core. However, this additional step of securing the liner to the mantle core requires additional time and increases labor costs for removal and affixing of the liner.
In general, the multi-sectional liner reduces the construction costs of each liner section and, also, extends the usable life of the upper liner. However, the entire main shaft still has to be removed and disassembled in order to replace a worn lower lining section. Therefore, the cost associated with removing and replacing the entire mantle core and the problems of affixation to prevent the axial movement of the sections still remain.
Another disadvantage of known mantle liner assemblies is that some liners must be machined to fit with certain mantle assembly parts. Such fitting requires that a close tolerance is machined into the liner to insure proper spacing for the above mentioned zincing and other attachments. Although some conventional liners have consisted of a support plate which can be made of mild steel thus increasing the ease of machining, the problems associated with this manufacturing step have still persisted. Furthermore, in the prior art, in liner assemblies where the support plate directly engages the mantle core having a wear surface (e.g., manganese steel) affixed thereto, machining of the support plate is needed for a proper fit and, as a result, increases labor and thus cost of the liner manufacture. Finally, in order to provide an effective fit between the support plate and a liner wear surface, an additional machining step may be needed.
Still further, it has been proposed in the prior art to use multi-sectional mantle liners comprised of numerous liner plates of highly abrasive resistant material arranged concentrically around the mantle forming a conical shaped surface. In this manner, the entire mantle liner is formed of these liner plates. However, these multi-sectional mantle liner plate assemblies must be constructed with an interlocking mantleliner design, which provides the interlocking of a liner with the mantle core or an adjacent liner plate or even a wear-ring. These limitations decrease the shapes and materials from which the liner plates can be made and, further, increase the costs of construction and maintenance replacement.
Yet another disadvantage of known multi-sectional mantle liner plate assemblies is the need to back each liner plate to the mantle by the conventional zincing processes. Even though these liner plate assemblies of the prior art reduce the labor costs to change the liner, the additional steps of securing each liner plate to the mantle core or to an adjacent liner or even a wear-ring have not eliminated the time or reduced the cost needed for affixation and removal of the liner. Therefore, the shortcomings associated with the step needed to adhere a number of liner plates to the core remain to increase the time and labor involved in replacing a multi-sectional mantle liner plate.